1. Field of the Invention
The present invention generally relates to a respiratory aid for the alleviation of breathing and airway disorders, and more specifically to a respiratory aid comprising a Venturi air pump.
2. Discussion of the Related Art
The present invention relates to respiratory disorders in which external devices are used for delivering respiratory gas to assist spontaneous or forced breathing. Although the invention relates in particular to sleep apnea, the device and method disclosed in the following are not limited to this particular use and can be utilized for the alleviation of other respiratory disorders as well.
Sleep apnea is a disorder characterized by full or partial cessation of breathing during sleep. Apnea is defined as an interruption in breathing (air-flow into the lungs) for at least ten seconds, accompanied by a decrease in oxygen saturation. Hypopnea is a milder form in which there is a 50% decrease in air-flow for more than ten seconds. The number of incidents in which there is an interruption in breathing define the severity of the disorder. Patients suffering from sleep-associated apnea may have as many as 300-500 such interruptions in air-flow per night, each lasting 30-40 seconds. Obstructive Sleep Apnea (OSA) is the most common apneic disorder stemming from a mechanical obstruction in the upper respiratory airways during sleep. It is caused by recurrent blockage or narrowing of the airways during sleep and reduction in oxygen saturation.
Following the period of cessation of breathing, an abrupt, but brief, waking occurs caused by the urgent need for oxygen. This requirement is met by a single powerful inhalation, usually accompanied by a loud snore. Since this phenomenon occurs many times per night, it causes a fragmented, and unsatisfactory, sleep pattern. As a result of the frequent oxygen deprivations during the night, the patient will experience tiredness and lassitude during the daytime, sometimes resulting in uncontrolled sleep episodes during waking hours. The severity of the sleep apnea is usually expressed by the average number of complete or partial blockages per hour.
A significant number of sleep apnea patients have been found to suffer from enhanced cardiovascular morbidity. In addition, sleep apnea has been shown to be a risk factor for: systemic hypertension, pulmonary hypertension, ischemic heart disease, acute myocardial infraction, and brain infarction. The daytime sleepiness and tiredness, associated with the fragmented sleep pattern, expose these patients to additional dangers such as traffic accidents and work-associated accidents.
The present invention addresses other breathing disorders as well. These include: intensive care patients requiring assisted breathing, post-operative patients, asthmatic patients, patients with emphysema, patients with severe lateral sclerosis, patients with chronic heart failure, multiple sclerosis patients, and other breathing-associated disorders.
People with moderate to severe OSA are usually treated with CPAP (Continuous Positive Airway Pressure). The CPAP device is essentially an air pump connected by flexible tubing to a mask worn by the patient. This forced air flow, the pressure of which can be regulated depending on the severity of the apnea in each individual, keeps the airways from collapsing, thus preventing the interruptions which result in the apneic episodes. A typical CPAP system is illustrated in FIG. 1A. It comprises an air blower 1 which supplies a continuous flow of compressed air at relatively low pressure, usually in the range 2 to 20 mbar (20-200 mm H2O). The air stream is forced through the flexible wide-bore (20-25 mm) tubing 2 to the mask assembly 3 placed on the patient's face and held in place by a head-encircling elastic straps 4. In order to keep a positive pressure inside the CPAP mask, the mask must have a peripheral seal. There exist a variety of CPAP masks varying from full-face masks covering both nose and mouth as mask 3 of FIG. 1A, through nasal masks which cover only the nose, and include nostril assemblies, as shown in FIG. 1B, in which the air is directly administrated to the nostrils. The nostril assembly of FIG. 1B is held by a curved plastic holder 6 affixed to the patient's head for supporting tubing 2. Tubing 2 terminates with a rigid short tube 7 connecting between tubing 2 and nostril piece 5 inserted into the patient's nostril.
The CPAP device has been proven to be successful in preventing breathing obstruction during sleep but it suffers from a number of drawbacks, associated mainly with discomfort to the user, as detailed in the following:                1. A CPAP apparatus is cumbersome to use because the mask and its straps are uncomfortable to wear. The mask assembly, together with the thick air pipe, limits the sleep positions of the patient and confines his/her ability to turn in their sleep. Since turning during sleep is an activity not controlled by the patient, the CPAP device itself may cause such discomfort as to wake the patient, and/or reduce the quality of sleep.        2. The apparatus requires connection to a power supply, which limits the mobility of the patient, and interferes with activities when an electrical outlet is unavailable (flights, camping, etc).        3. Since the device supplies a constant positive airflow through the mask, the user is forced to exhale at a pressure greater than the incoming flow of air in order to overcome the blower pressure. This is particularly true for a CPAP having a full-face mask, but also for situations with a nasal mask when the patient exhales through the nose. This necessity runs counter to the natural breathing rhythm during sleep, and requires adaptation.        4. When using the more common nasal mask, the patient is often forced to exhale through the mouth, resulting in dryness of the oral cavity during the night.        5. Since the air flows under relatively low pressure, it must be forwarded in large diameter pipes. If a smaller diameter pipe is used, it will decrease the air pressure intended for breathing and the apparatus will lose its efficiency.        6. When temporarily there is no need for the device, it is the practice to disconnect the device from the user due to the discomfort of wearing the mask and the restrictions to the user movements when connected to the device. When the need returns, the device has to be fitted again.        
Thus, in spite of the undoubted benefit of CPAP devices in preventing apneic episodes, it was found that many patients tend to stop using the device after a period of time due to discomfort.
Accordingly, it is the general objective of the present invention to provide device and method that supply the necessary positive airflow to prevent airway collapse while overcoming the disadvantages of present CPAP devices.
In particular, it is one object of the invention to provide a respiratory aid apparatus that minimizes discomfort to the user, is light in weight, is mobile, and can be operated by batteries independently of electric current supply.
It is another object of the invention to provide a respiratory aid method and system that allow control of airflow according to the needs of the user and that allow regulating the airflow during the respiration cycle, making the breathing process more normal and comfortable.
Yet it is another object of the invention to provide a respiratory aid method and system that can be easily turned on or off and that when turned off allows for a normal breathing with no need to disconnect the user from the system.
Yet it is a further object of the invention to provide a respiratory aid system and method that not only delivers airflow to the user during inhalation phase but further provides active removal of air from the user airways during the exhalation phase.
A further object of the invention is to provide a respiratory aid apparatus that can be used with any currently available breathing mask, and is small, effective, easy to manufacture and is of low cost.
Yet a further object of the invention is to provide a novel user interface unit that can replace currently available breathing masks, and is small, flexible, can be easily adjusted to fit the user and is much more comfortable than currently available masks